Serena Williams won the clash between two of the hottest players on the WTA Tour with a straight-set victory over Swiss Timea Bacsinszky at Indian Wells on Wednesday.
World number one Williams extended her match win streak to 15 by beating the red-hot Bacsinszky 7-5, 6-3 on the Tennis Garden stadium court.
Bacsinszky's fourth round win over Elina Svitolina was her 15th consecutive match win, including Fed Cup play.
Williams now faces third seeded Simona Halep after the Romanian beat Spain's Carla Suarez in three sets.
Williams got past her in one hour and 25 minutes. She belted seven aces but also had four double faults and said she needs to step up her game.
Halep came storming back from an opening set loss to beat Suarez 5-7, 6-1, 6-1 and advance to her second straight Indian Wells semi-final.
Halep has gone three sets in three of her four matches in Indian Wells. But she says she doesn't mind the extra time on the court because it allows her to perfect her game.
Halep hit two aces, committed three double faults and broke her opponent eight times in the close to two-hour match.
Williams leads Halep in their head-to-head series four game to one but the loss wasn't that long ago. Halep beat her 6-0, 6-2 at the 2014 WTA Tour finals in Singapore.
World No1 Novak Djokovic took another step towards defending his Indian Wells title with a hard-fought 6-4, 7-6 (7/5) win over American John Isner on Wednesday.
Djokovic has struggled in the past with the 6-foot-10 (2.08m) Isner's bombing serve on the hardcourts of the California desert.
But the reigning Australian Open champ got the best of his opponent in the key tiebreaker.
Djokovic booked a quarter-final clash with 35th-ranked Bernard Tomic of Australia.
Tomic eliminated fellow Aussie Thanasi Kokkinakis 6-4, 4-6, 6-4.
Djokovic now has a 6-2 advantage in career meetings, with nine of the sets going into tiebreakers. Isner has won six of those, so Djokovic felt fortunate to squeak through this time.
Djokovic hammered seven aces and saved both break points he faced in the one hour, 31 minute match.
Four-time Indian Wells winner Roger Federer needed just 69 minutes to oust American Jack Sock 6-3, 6-2.
In the quarter-finals, the Swiss second seed will face ninth-seeded Czech Tomas Berdych, a 6-2, 4-6, 6-4 winner over compatriot Lukas Rosol.
Federer and Berdych have met 18 times with the Swiss holding a 12-6 lead.
World number three Rafael Nadal rolled over France's Gilles Simon 6-2, 6-4.
The left-handed Spaniard hammered four aces and broke Simon five times to set up a meeting with hard-hitting Milos Raonic of Canada.
Raonic hammered a 241 kmph (150 mph) serve en route to a 6-3, 6-2 straight set win over Tommy Robredo of Spain.
Raonic is in his second straight quarter-final but he will have his work cut out for him because he has never beaten Nadal in five career meetings.
Fourth seeded Andy Murray, trying to rebound from a subpar 2014, defeated Adrian Mannarino 6-3, 6-3 in the fourth round.
Murray next faces Spain's Feliciano Lopez who upset fifth seed Kei Nishikori of Japan 6-4, 7-6 (7/2).
Maria Sharapova suffers a shock defeat by Flavia Pennetta at the BNP Paribas Open. Briton Heather Watson is also eliminated but there are wins for Simona Halep and Serena Williams in California.